Fascinating piece on BBC4 last night, a documentary on James Randi, psychology and magic. In his long career as a magician and debunker, Randi exposed fraudsters like Peter Popoff:
https://en.wikipedia.org/wiki/Peter_Popoff#Investigation_by_James_Randi
An interesting line in the program was that, even when people know they are being lied to, the prefer to believe the lie rather than the truth. Hence the resurgence of Peter Popoff even after he had been shown as a despicable con artist who took money off people and told them they were cured of all sorts of illnesses.
While watching, the parallels with the current American politics were apparent. People will willingly listen to and vote for "We're going to build a wall", "We're going to keep the Muslims out", "We're going to make America great again" and they may even know these things are untrue or unlikely - but they'll vote for it anyway, because it's want they want to hear.